The present invention relates to the cleaning and disinfecting arts. It finds particular application in conjunction with the cleaning of animal cages and racks and also healthcare and scientific equipment, such as hospital beds, wheelchairs, utensils, carts and instrument containers, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to the cleaning and disinfecting of other pieces of equipment, particularly those which have been in contact with biological wastes.
Items such as animal cages and associated racks and large pieces of healthcare and scientific equipment are generally cleaned at frequent intervals to remove biological waste, such as urine, feces, and uneaten food. Thorough cleaning aids in preventing the spread of disease and reduces the development of unpleasant odors. Washers have been developed to handle the large scale cleaning and disinfecting of animal such items. Typically, these are large enough for a load to be processed to be wheeled manually into the washer. Cleaning fluid is then sprayed through jets onto the load. The used fluid is collected in a pit or sump, below the washer. The fluid is either recycled or discarded, depending on the degree of contamination.
When large numbers of items are to be cleaned, the cycle time of the machine is an important factor. A washer for items such as cages is necessarily a large and invariably a costly investment, and it is thus desirable for a facility to clean all such items in a single washer. Typically, the jets which are used to spray cleaning fluid over the load operate at around 20 p.s.i. (1.4 bar). Stripping the often dried and adherent biological matter from the load with fluid at this pressure is time consuming and cleaning cycle times of 40 minutes or longer are common. In addition, low pressure washing uses large quantities of cleaning fluid to compensate for the low level of impingement of the sprays upon the process load.
The length and effectiveness of the cleaning system are also dependent on the arrangement of the jets within the washer. Cages and racks and scientific and healthcare equipment and racks are often large, with components which inhibit movement of the cleaning fluid, resulting in incomplete cleaning of the load. A number of systems have developed for directing the sprays of cleaning fluid so as to improve coverage of the load. In one system, a rotary spray arm is used. The pressure of the cleaning fluid causes the arm to rotate. Holes in the spray arm spray the fluid into the washer. The effectiveness of cleaning, however, is reduced because the sprays emitted tend to fight against each other, reducing the power of the sprays and varying their direction. Some of the energy of the spray is utilized in rotating the spray arm, reducing the water pressure efficiency of the spray. It is also difficult to ensure coverage of the entire load with a rotating spray arm. Further, the soil washed from the load tends to be pushed toward the center of the washer, collecting on parts of the load, rather than dripping off the load and into the sump.
In another cleaning system, a tube supplies cleaning-fluid to two spray bars or arms, movably mounted on either side of the washing chamber. The bars move simultaneously up the side of the washer, spraying fluid from nozzles as they travel. The sprays provide coverage of the entire washer, and increase cleaning efficiency through the effect of fluid dripping through the load. The system generally includes a complicated movement mechanism. A safety clutch is therefore provided to reduce the danger to workers in the event that the mechanism fails to operate properly. The sprays from the two spray bars tend to fight against each other. In a similar cleaning system, spray arms travel horizontally, rather than vertically. In addition to having some of the problems associated with the vertical cleaning system, the sprays tend to push the soil into the center of the load, resulting in less efficient cleaning.
There remains a need for a cleaning system with a reduced cycle time that strips the biological matter from the load and sanitizes the load more effectively.
Effective cleaning of the load is also achieved by maintaining the concentration of a selected detergent in the cleaning fluid. Because of the often high cost of the detergent, and the large quantities of cleaning fluid employed, it is desirable to maintain the detergent concentration close to the minimum level required to insure effective cleaning. Traditionally, the cleaning fluids are pumped in solution from storage tanks. Periodically, the fluid in the tank is replenished by the separate addition of detergent, in concentrated form, and water.
Measuring the actual concentration of the detergent in the tank is time consuming, therefore methods have developed which determine the concentration indirectly. Typically, one of two methods is used to estimate the concentration of detergent. In the first method, the addition of detergent to the tank from a detergent supply container is timed. The concentration of detergent is inferred from the operating time of a pump used to transfer the detergent. This provides a simple means of determining detergent concentration. However, if there is little or no detergent passing through the pump, which could occur, for example, if the pump is not working properly, then inaccurate measurements of detergent concentrations are obtained. Inadequate cleaning and sanitization of the process load results when the detergent concentration drops below a minimum level.
In the second method, the detergent concentration is inferred from a measure of the pH or conductivity of the cleaning solution. This correlates well with the detergent concentration in the fresh cleaning fluid. It is usual, however, to recycle a portion of the cleaning fluid from the washer into the tank for reuse. The recycled cleaning fluid contains soil from the load which influences the pH and conductivity of the cleaning fluid. Thus, the measure of pH or conductivity gives an inaccurate determination of the concentration of detergent in the tank, the inaccuracy becoming more pronounced at higher soil concentrations. There remains a need for a cleaning system that insures effective cleaning by providing a more accurate method of monitoring the rate of addition of detergent.
The cleaning fluid is generally retained in the sump. The cleaning fluid is pumped from the sump by a sump pump and circulated to the nozzles in the washing chamber. The fluid level in the sump must remain deep enough that the sump pump does not cavitate. Conventionally, cage and rack washers employ sumps of around 30-40 cm deep to supply the necessary depth of fluid for operation of a typical sump pump. To provide this depth, a large well is usually constructed through the floor beneath the washer, with suitable reinforcement for the washer. Constructing such a well within a concrete floor is frequently expensive and time consuming. In some floor structures, there is insufficient below ground depth available for the sump and the load is raised well above floor level to enter the washer. Ramps provide a means of raising the load, but as cages and hospital and scientific equipment are frequently heavy, it is difficult to push them up a ramp that is too steep. Shallow ramps make loading the washer easier but take up considerable space and are hazardous if wheeled carts are left unattended and accelerate down the slope.
Typically, a portion of the cleaning fluid is returned to the tanks for recycling after it has been used in the washer. Generally, sump pumps do not begin to operate until a sufficient head of fluid has collected in the sump. Thus, there is a delay between cycles while a portion of the used cleaning solution is discarded and replaced with fresh water and added detergent. In addition, because of the different soils encountered, cleaning systems typically include two or more cycles, each using a different cleaning fluid. Separate tanks are used for each of the cleaning fluids. To avoid mixing of the different fluids, the contents of the sump are pumped to the tanks between cycles. There is a considerable time lag between cycles as the pump completes the removal of the collected fluid from the sump. Moreover, the pump ceases to operate once the fluid drops below the cavitation level and the remaining fluid is simply drained to the waste system. Draining of the sump in this way takes considerable time, and also increases operating costs through higher detergent use and costs of treating the waste to meet environmental standards.
The fluid collecting in the sump is typically heated by a steam coil, located in the sump, to maintain the temperature of the fluid during cycles. Because of heat losses from the sump compounded by the length of time spent by fluid in the sump, considerable wastage of energy occurs. In addition, the fluid in the sump is heated to a higher temperature than that employed in the washer to compensate for cooling. The hot soil-contaminated cleaning fluid and steam coil pose a danger to workers entering the washer between cycles, if they should accidentally fall into the sump. There exists a need for a cage washer that operates without a deep sump and that allows rapid removal of the used cleaning fluids from the sump. There also exists a need for a cleaning system which minimizes heat losses from the cleaning fluid.
Because of the cost of detergents, it is beneficial to reuse as much of the cleaning fluid as possible. Traditionally, a filter system removes solid matter from the used cleaning fluid before the fluid is returned to the fluid tank which filter becomes clogged with the solid material. The solid material clogging the filter reduces the wash pressure and efficiency of cleaning. Periodic down-time for manual cleaning of the filter is, therefore, encountered. This filter cleaning time limits the operating period of the washer, reducing the number of loads processed in a given time. There is a need for a filter system which operates continuously, flushing the build up of solid material from the filter without the need for frequent cleaning of the filter.
The present invention provides a new and improved washer with an improved cleaning system which overcomes the above referenced problems and others.
In accordance with one aspect of the present invention, a washer is provided. The washer includes a washing chamber, with spray nozzles disposed in the washing chamber for spraying a cleaning fluid over a load to be cleaned. A sump at the bottom of the washing chamber collects the cleaning fluid sprayed over the load. A sump pump removes cleaning fluid from the sump. A high pressure pump pumps cleaning fluid from a cleaning fluid reservoir to the spray nozzles.
In accordance with another aspect of the present invention, a washer is provided. Spray nozzles disposed within a washing chamber spray a cleaning fluid into the chamber. A pump pumps cleaning fluid to the spray nozzles from a cleaning fluid reservoir. A vertical traveler includes first and second counterbalanced spray arms, disposed adjacent opposite sides of the washing chamber, the spray nozzles disposed on the spray arms. The traveler also includes a mechanism which supports the spray arms for vertical travel and a drive system which alternately raises and lowers the spray arms, the first spray arm traveling in an opposite vertical direction to the second spray arm.
In accordance with yet another aspect of the present invention a washer is provided. Spray nozzles disposed in a washing chamber spray a cleaning fluid over a load to be cleaned. A pump which pumps cleaning fluid from a cleaning fluid reservoir to the spray nozzles. A filtration device removes suspended material from the cleaning fluid. The device includes a fluid inlet which receives cleaning fluid and a first fluid outlet which directs unfiltered cleaning fluid from the filtration device to a drain. The device also includes a valve which selectively closes to prevent cleaning fluid from exiting the filtration device through the first fluid outlet. The device further includes a filtration screen which filters suspended material from the cleaning fluid and a second fluid outlet through which filtered cleaning fluid leaves the device.
In accordance with another aspect of the present invention a fluid injection system for insuring accurate delivery of a preselected quantity of a fluid is provided. A peristaltic pump delivers the fluid, the preselected quantity of fluid measured in terms of a number of pulses of fluid delivered by the pump. A flow meter indicates whether fluid is flowing through the pump, the flow meter detecting a flow of fluid in the fluid injection system.
In accordance with another aspect of the present invention, a method for cleaning large equipment is provided. The method includes supplying spray nozzles with a cleaning fluid at a high pressure and spraying the cleaning fluid from the spray nozzles over a load of equipment. The method further includes collecting sprayed cleaning fluid in a sump and draining the cleaning fluid from the sump with a sump pump.
In accordance with another aspect of the present invention, a cleaning system is provided. The system includes supplying spray nozzles with a cleaning fluid and spraying the cleaning fluid from the spray nozzles over a load to be cleaned. The method also includes sequentially raising and lowering the spray nozzles with a vertical traveler. The sequence includes raising a first set of the spray nozzles at the same time as lowering a second set of the spray nozzles. The sequence further includes lowering the first set of the spray nozzles at the same time as raising the second set of the spray nozzles.
In accordance with another aspect of the present invention, a cleaning system is provided. The system includes supplying spray nozzles with a cleaning fluid at a high pressure, spraying the cleaning fluid from the spray nozzles over a load to be cleaned and collecting sprayed cleaning fluid. The system also includes closing a filtration valve connected to a first outlet on a filtration device and passing the sprayed cleaning fluid into the filtration device. The system further includes filtering suspended material from the sprayed cleaning fluid and passing the filtered cleaning fluid from the filtration device through a second outlet. Still further, the method includes selectively opening the filtration valve and allowing a portion of the sprayed fluid to pass through the first outlet and through the open filtration valve to remove suspended material trapped within the filtration device.
One advantage of the present invention is that the cycle time for the washer is considerably reduced over conventional systems.
Another advantage of the present invention is that it enables optimal detergent concentrations to be maintained with minimal detergent additions.
Yet another advantage of the present invention resides in its effective cleaning, with lower volumes of cleaning fluid.
Still further advantages reside in the shallow depth of the sump, simple installation, and the low volume of cleaning fluid remaining therein between cycles.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.